ESTABLISHED BY EDWAKD L. YOUMANS. 



THE 



POPULAK SCIENCE 



MONTHLY. 



EDITED BT WILLIAM J. YOUMANS. 



VOL. XXXI. 



MAY TO OCTOBER, 1887. 



NEW YORK : 



D. APPLETON AND COMPANY, 



1, 8, asd 5 BOND STREET. 



1887. 



